Pratt & Whitney announced Monday that it has received a $437 million addition to a Pentagon contract for development of next generation fighter jet engines.

Pratt and General Electric are competing to develop the sixth-generation fighter jet engine for the U.S. military.

The contract modification brings the total value of the contract to $1.45 billion for designing, fabricating, integrating and testing complete, flight-weight adaptive engines, the Defense Department said.

Work is to be done in East Hartford and to be completed by 2022, the contract listing states.

"We look forward to continuing the maturation of adaptive engine technologies in collaboration with the U.S. Air Force for the next generation of combat aircraft," Chris Flynn, vice president of military development programs at Pratt & Whitney, said.

"We are committed to giving the warfighter a technological advantage."

In July 2016, Pratt and GE each received billion-dollar contracts from the Defense Department to develop the next generation of jet fighter engines. That competition had an end date of September 2021, which the contract modification pushes to Feb. 28, 2022.

The companies are working on engines to power the next generation of jet fighters, with a rivalry that dates back to the 1980s, when Pratt won an exclusive contract to build engines for the F-35 Joint Strike Fighter. GE opposed that decision.

In a similar announcement in late June, the Defense Department awarded an identical contract extension to General Electric with the same language used in its Friday announcement of the award to Pratt.

"The Department of Defense funding is still divided equally between Pratt and GE," Pratt spokesman John J. Thomas said. "The competition is not yet decided. This continues research and development on the attempted engine."

Pratt said in addition to its demand-modulated engine design, it is also working on an adaptive technology suite including control, power, and thermal management systems to enable improved range, persistence, survivability, and maintainability for advanced weapon systems.

Pratt said research and technology will advance fifth-generation engine technology and support the Adaptive Engine Transition Program, a Pentagon effort to prepare for sixth-generation work.

Thomas said information for the project is classified, but in a statement, General Electric said it has tested three-stream fan configurations, a compressor rig, two full-scale propulsion systems, and a three-stream technology demonstrator engine in the last decade.